As the number of mobile computing-based devices in an organization grows, the set of machines connected to the organization's network becomes more dynamic. This occurs as machines leave the organization's network, potentially join other untrusted networks and then return to the organization's network. For example, employees may take laptop computers home and view Internet sites or share files via various public and private networks.
Every time a machine migrates among networks outside the organization's network, the machine can be exposed to malicious agents, including malware such as viruses, worms, etc. These malicious agents can then be introduced to the organization's network when the infected machine is reconnected to the organization's network. In this way, potentially all of the resources connected to the organization's network can be exposed to a variety of malicious agents.